Sound suppressing ventilator fitment for wall apertures



E. T. FISK 1,816,769

SOUND SUPPRESSING VENTILATOR FITMENT I FOR WALL APERTURES July 28, 1931.

Filed June 27, 1928 F/Gl.

INY em-ro Patented July 28,1931

PATENT OFFICE ERNEST THOMAS FISK, OF SYDNEY, NEW SOUTH WALES, AUSTRALIA BOUND SUPPRESSDTG VENTILATOB FITMENT FOB AIRTUBEQ Application filed June 27, 1928, Serial No.

The object of this invention is to rovide means for facilitatin ventilation t rough apertures in walls of guildings and through window openings whilst limiting transmission of sound in theincoming air. The invention is susce tible of a variety of applications. It ma or instance, be used to admit ventilation t rough an open window while suppressing the transmission of street noises into an apartment. It may be fitted to an existing door or it may be utilized as an auxiliary door to permit ventilation but to impe e transmission of sound vibrations throu h it when the main door hung'in the same mine is left open. Or it may be utilized in a partition between two apartments to facilitate circulation of air between these apartments whilst impeding transmission of v sound from one apartment to the other. The invention comprises a cellular screen or panel having airways through it by which ventilating air-currents can pass, but in which sound waves in the air are absorbed, re-

fracted, or deflected'and are not transmitted as with the ventilation air except in asubstantially damped state.

In the accompanying drawings Fi 1 is a sectional perspective view of a venti ator built into a wall;

Fi 2 is a fragmentary detail section of a vent ator similar to Fig. 1;

Fig. 3 is a fragmentary section of a modification ofthe ventilator; and

Figs. 4 and 5 are detailsectional views of further modifications.

In Figs. 1 and 2 the device is shown as a hollow box 15 having non-aligning perforations 16 through the inner and outer sides of it, and lined with felt or other sound dead-,. .ening material 17. The energy of sound vibrations in the inassing air is largely absorbed in the midliamber 14 and the air passes through the cellular passa es 16 on the inner side of the panel in a su -divided stream and with the sound vibrations abstracted or damped.

Observation of results obtained in the use of such sound chamber panels suggests that they facilitate or at any rate only no li- 60 gibly retard air flow through them w en through which air flow takes place.

288,784, and in Australia July 27, 1927.

wind blows against their external sides. But vibratory or oscillatory conditions in the inpassing air are broken down or absorbed and dissipated particularly when the air passages or the mid cell are lined with felt, soft rubber, or other non-sonorous material.

The functioning of the panels ma be exalted so that they will more complete check noise transmission without toofar limiting freedom for circulation of ventilation by fitting oneor more perforate septa across the mid cell, and alsoby disposin the perforations in the inner septum and t e anel sides staggered or out of alignment ei er by displacing them laterally or by varying their direction.

surfaces with which"; the incoming air contacts', are constructed of or lined with felt or other non-resonating material in which sound waves will be absorbed, but useful results are 'still attained with structures of metal, glass, artificial stoneware or other hard material by reason of the disposition of the surfaces to deflect, reflect, and baflle sound vibrations.

Fig. 3 illustrates a form of the invention in which the innerand outer walls 18-19 of a hollow box are perforated at 20 and a perforate septum 21 1S fitted in the chamber 22. This view .ggests a construction in stone ware or like nis -erial, unlined.

A screen of louv e type is efiicient so long as the intervening louvre slats are disposed so that they operate to break upthe wave front, the air vibrations carried past them being broken down by absorption or deflection M in chambers within the strugturfi a screen is shown in Fig. 4, in which the encasement 23 is fitted with oppositely p tched louvres 24 in the respective sides of it. septum 25 may be, fitted in the chamber 26 between the frontal and rear side louvres. This semptum may be a perforate sheet of non-sonorous material, or it may be a sheet of cloth or felt ap ropriatel perforated Fig. 5 shows anot er modi cation in which The highest efficiency is attained when the the air currents and to procure damping of a. perforate plate 30 forms one side of the panel, and louvres 31 the other side of it, the septum being formed by reveraely pitched louvres 32.

What I claim as my invention and desire to secure by Letters Patent is A sound damping ventilating sereen hav- 7 ing perforated sides including sound dampemng material forming the walls of the perforations,said screen having an air chamber between the perforated sides, and a perforate septum in said chamber.

In testimony whereof I afiix my si ature.

ERNEST THOMAS F 18K 

